[Java Basics] Let map value self-increment

Requirements: I want to determine in the map whether there is a key, there is a key corresponding to the value = value+1, otherwise set <key,value=1>

The code is implemented in the following way:

ContainsKey

Import Java.util.HashMap; Import Java.util.Map, ..... MapNew hashmap<string, integer>(); .. int count = Freq.containskey (word)? Freq.get (Word): 0+ 1);

Testfornull

Import Java.util.HashMap; Import Java.util.Map, ..... MapNew hashmap<string, integer>= freq.get (word); if NULL ) {    1);} Else {    + 1);}

Atomiclong

Import Java.util.concurrent.ConcurrentHashMap; Import Java.util.concurrent.ConcurrentMap; Import Java.util.concurrent.atomic.AtomicLong, ..... Final concurrentmap<string, atomiclong> map =     new concurrenthashmap<string, atomiclong>  New Atomiclong (0)); Map.get (word). Incrementandget ();

Trove

Import Gnu.trove.TObjectIntHashMap, ..... TobjectinthashmapNew tobjectinthashmap<string>1, 1);

Mutableint

ImportJava.util.HashMap;ImportJava.util.Map, .....classMutableint {intValue = 1;//Note that the We start at 1 since we ' re counting   Public voidIncrement () {+ +value; }   Public intGet () {returnvalue;}} ... Map<string, mutableint> freq =NewHashmap<string, mutableint>();... Mutableint Count=freq.get (word);if(Count = =NULL) {freq.put (Word,Newmutableint ());}Else{count.increment ();}

There are also ways to Java8:

Map.merge(key, 1, Integer::sum) //如果key存在，就调用sum 1 到map的value，如果key不存在，put（key，1）

   < Span class= "pun" >< Span class= "PLN" > time, execute 1000 times, as shown below 
 

Time                  , mskolobokecompile  18.8koloboke         19.8trove            20.8fastutil          22.7mutableint       24.3atomicinteger    25.3Eclipse          26.9  HashMap          28.0hppc             33.6hppcrt           36.5

[Java Basics] Let map value self-increment